Thanks
to local aquarium stores nationwide, the first fishes introduced
to aquarists, and added to their aquariums, are generally
damselfishes. They are sold as fish that are incredibly hardy,
usually withstanding all that new hobbyists can give them,
and then some. In this regard they probably are the ideal
fish for first-time hobbyists. The time will likely come,
however, when the aquarist will need to remove these fish
from the aquarium in order to keep the peace or be able to
add additional, less pugnacious fish. Unfortunately, this
often either is not discussed prior to the damsels' introduction,
or the aquarium store employees fail to relate and detail
the tedious work required to remove the fish. The ensuing
attempts to catch and remove these fish will undoubtedly stress
the hobbyist, the fish they are trying to catch, and naturally
any other inhabitants of the aquarium. Perhaps the most apt
present for those less-than-well-liked hobbyists
on your Christmas list should be damselfish of the genus
Stegastes.

The juvenile color form
of Stegastes planifrons might as well be
called the wise-man's Rock Beauty Angel because
of the poor track record of the Rock Beauty when
compared to the survivability of the Threespot
Damsel. Adult photo (left) courtesy of
John Randall. Juvenile images (above &
below) courtesy of Henry C. Schultz III.

Meet the Family

The
common name "damselfish" is applied to over 300
marine fish and as a group name, it is accurate enough for
hobbyists. Ichthyologists categorize them as belonging in
the taxonomic family of marine fish family called the Pomacentridae.
This family presently contains 28 genera divided among the
four subfamilies. The subfamily Pomacentrinae is where you'll
find Stegastes, the feature of this month's column.

Subfamilies
of Pomacentridae:

Amphiprioninae

Chrominae

Lepidozyginae

Pomacentrinae

The initial naming of Stegastes
occurred when Forster (1801) released his manuscript detailing
a new species of fish he chose to call Stegastes lividus.
Shortly thereafter, Lacepede (1802) proclaimed Stegastes
nigricans as a valid species, but he opted to name it
Eupomacentrus, another new generic name for damselfish.
Species that are now considered Stegastes were continually
added to either genus until Bleeker (1877) revised the genus,
declaring Stegastes a junior synonym and a subgenus
of Eupomacentrus. Subsequently, Emery and Allen (1980)
reinvestigated the genus, and resurrected Stegastes,
and placed Eupomacentrus as a synonym of Stegastes.
Perhaps interesting to note - the species that were classified
under the subgenus of Stegastes were moved to Plectroglyphidodon
upon Stegastes elevation to genus.

Considering the outgoing, defensive nature
of damselfish, especially those of Pomacentrinae, I find it
surprising that new species are still being uncovered. Even
so, new additions have been added as recently as 1999 (Stegastes
trindadensis), 2000 (S. uenfi) and 2001 (S.
robertsoni). Currently, there are 38 species in the genus
Stegastes.

Pomacentridae

*
Pomacentrinae


Stegastes

§
acapulcoensis

§
adustus

§
albifasciatus

§
altus

§
apicalis

§
arcifrons

§
aureus

§
baldwini

§
beebei

§
diencaeus

§
emeryi

§
fasciolatus

§
flavilatus

§
fuscus

§
gascoynei

§
imbricatus

§
insularis

§
leucorus

§
leucostictus

§
limbatus

§
lividus

§
nigricans

§
obreptus

§
otophorus

§
partitus

§
pelicieri

§
pictus

§
planifrons

§
rectifraenum

§
redemptus

§
robertsoni

§
rocasensis

§
sanctaehelenae

§
sanctipauli

§
trindadensis

§
variabilis

§
uenfi

In the Wild

Both the Atlantic
and the Pacific Oceans have populations of Stegastes,
and species from each ocean are common in the aquarium trade.
Six species are regularly encountered in the Caribbean; the
remaining 22 species are spread across Pacific waters including
not only the North and South Pacific, but the Indian Ocean
and Red Sea as well. Some species, such as S. fasciolatus
and S. albifasciatus, range over a large geographical
area incorporating most of the reefs from the east coast of
Africa to as far east as Easter Island. However, whereas S.
fasciolatus has a considerable expansive latitudinal distribution,
stretching from the temperate seas of Japan to the temperate
seas of the Great Barrier Reef, the distribution of S.
albifasciatus is restricted to the tropical seas not stretching
far from the equator. In contrast, S. pelicieri, the
species with the smallest geographical distribution, is found
only around Mauritius (Allen and Emery, 1985).

Stegastes pelicieri is noted to remain as a solitary
individual throughout its life. Photo courtesy of John
Randall.

The Australian Gregory, Stegastes apicalis, can be
found along the entire Great
Barrier Reef and is rarely found deeper than 20 feet. Photo
courtesy of John Randall.

Populations of Stegastes species
may sometimes be found in small, loosely fit aggregations,
but a solitary lifestyle is more likely, or possibly a relationship
with a conspecific of the opposite sex. Despite the wide berth
given to each pair by the neighboring pair, they often outnumber
all other fish species on the reefs of which they inhabit.
A couple of factors may play important roles in this. First,
they do not actually inhabit a true reef, but instead opt
for dying thickets of branching coral, large boulders, man-made
structure, and even garbage. Second, they are often found
in water no deeper than 20 feet, eliminating all but the juveniles
of many other genera of fish from competition for their desired
abode. Finally, these species are downright aggressive and
are afraid of virtually nothing. They will attack anything
that moves into their territory.

Aggregations of Stegastes bicolor feed cautiously
from the water column as a predator looms nearby. Photo
courtesy of Henry C. Schultz III.

Allow me to backtrack for a moment. The reader may wonder
why these damselfish would take up refuge in the lifeless
surroundings of garbage, pier pilings, and dead coral skeletons.
After all, surely a nearby reef blooming in astounding colors
from its multitude of corals would be the first choice, given
the other option of non-living, drably colored, and often
algal-infested rubble mounds. Considering that the one doing
the choosing is also among the biggest bullies with fins,
I can begin to understand why you might be left at bit perplexed.
The answer, my friend, lies in the healthy crop of filamentous
algae typically found in these locations. What is possibly
the single largest problem affecting unhealthy reef aquariums
world-wide is completely relished by these nasty little fish.
Not only do they desire endless fields of hair algae, but
they encourage its growth by farming it. Furthermore, they
will defend it to their death. They will rise no more than
10-15 feet at a maximum above their algae garden, and even
then only to chase away hostiles (DeLoach, 1999). They will
remain with the same patch of algae until another member forcefully
ejects them or they die. The total size of the algae mat depends
solely upon that particular fish's ability to defend it. The
more dominant the individual, the larger its territory. The
reason for this nonsense? The algae are the food source of
the damsel, and the farming and defending is their way of
ensuring they have a meal ready for tomorrow. Algae represent
50% - 90% of Stegastes diet, with the remainder consisting
of detritus and benthic invertebrates which are consumed as
the fish devour the algae mats.

Typically, the depths they inhabit, as
mentioned above, are shallow. Additionally, at each locale
the depth zone's range is minimal for all but a few species
(Allen and Emery, 1985). As always, a few species stand out
as exceptions to the rule. Stegastes altus, S fasciolatus,
and S. gascoynei have all been noted to range from
the surge zone to depths of nearly 100 feet at the same locale.

The Japanese Gregory, Stegastes altus, is not
widespread enough to make it a regular import for aquarium
purposes. The bottom two rays of the pectoral fin are
unique for the genus - they are not attached via the
membrane but isntead are free-formed. Photo courtesy
of John Randall.

Stegastes species use a number of methods to communicate
with conspecifics, particularly during spawning. Similar to
many marine fish, probably the most frequently encountered
correspondence is males displaying or flashing brightly accented
colors to females. Take, for example, Stegastes partitus,
which is normally 50/50 black and white. When trying to attract
a female, the fish becomes predominantly black and only the
base of the tail remains white. The tail itself, which is
normally white, matches the black of the body's torso. These
color highlights are usually associated with a series of mating
dances consisting of a series of quick, short bursts in one
direction followed by a nearly immediate reversal of direction.
Finally, individuals of Stegastes species will produce
audible grunts. The grunts are most often produced at the
apex of their spawning dance.

Of course, before the male does anything to attract a female
he must first get the nest in ideal condition for the female's
eggs. The selected site usually is a hard surface such as
rock, pier pilings, or dead coral. The male removes all algae
and foreign objects, as well as any offending invertebrates
such as urchins or starfish, from the area. The tail is used
to dust away detritus, while they grasp bulkier items such
as algae in their jaws, then remove them by swimming away
and dropping them. Mobile invertebrates which often have a
good grasp on the rockwork are chased away in similar fashion
to how these fish chase away SCUBA divers - persistent nipping
of their extremities.

A clutch of eggs laid by a Stegastes species.
Note how they are spread thinly over a large area. Photo
courtesy of Henry C. Schultz III.

Once a female accepts the proposition of a particular male,
she follows his lead to the nest where she lays a single layer
of eggs, which are attached to the rock's surface. The male
follows right behind the female and fertilizes the eggs. Females
then require several days of rest before spawning again, but
males are able to fertilize another clutch of eggs the following
morning; thus, he goes right back to work displaying to females.
Additionally, it is up to the male to ensure the eggs are
tended, although females occasionally may join in on the exercise.
Tending the eggs requires removing detritus that has settled
on the eggs, providing water movement which encourages proper
oxygen levels, and removing eggs that are either unfertilized
or that have contracted a bacterial infection. Roughly one
week after laying, healthy eggs have hatched and enter the
pelagic stage of their life cycle. After spending roughly
one month at the bottom of the food chain, the larvae settle
into the shallow waters away from established adult feeding
and spawning territories. Perhaps in an attempt to avoid aggression
from adults, the juveniles look nothing like their adult coloration.
Only after they gain size will they transform into their adult
coloration and venture into the adult habitat, joining other
sexually mature Stegastes species.

Some species of Stegastes exhibit a different
coloration depending on locale. A good example of this
is seen in the above two photos of S. fasciolatus,
simply called the Pacific Damsel. The image on the left
was taken in the Maldives, while the image on the right
is a Hawaiian specimen. Photos courtesy of John Randall.

Naturally, a similar group of the communication
tools used in spawning is also used as a precursor to attacking
intruders. If these warnings are not heeded, an all out assault
on the intruder will result. Unafraid of the largest parrotfish
or even SCUBA divers, attacks on the skin begin. Most often,
the parrotfish and other fish species will move along before
outward attacks are launched, but humans are usually not as
lucky. Fortunately, their small mouths and Velcro-like teeth
are unable to inflict damage beyond an increase in the diver's
heartbeat from being startled.

For a short video of a male both providing
maintenance and defending his clutch, click the video button:
The
video and pop-up window may take a few minutes to load depending
on your connection speed. The QuickTime plug-in is necessary
to view this video. To download the plug-in click on the image
below:

These photos of Stegastes diencaeus show just
how remarkable of a color change occurs as Gregories
transform from their juvenile stage to adulthood. Photos
courtesy of John Randall.

In the Home Aquarium

Similar
to many damsels, the members of Stegastes are characterized
as popular reef aquarium fish. To say any particular damselfish,
and specifically those of the genus Stegastes, is a
hardy aquarium inhabitant would probably be considered an
understatement by many hobbyists with experience with these
fish. They are resilient to the common mistakes made by beginning
aquarists, often to the extent of being able to survive for
extended periods of time variations in water parameters that
would kill most reef animals. This is obviously why damselfish
are suggested to be the first fish into the aquarium by most
local marine aquarium stores.

A preserved specimen of Stegastes emeryi is seen
here. Unfortunately, the photo does not show the wonderful
blue spots that are prevalent in this species. Photo
courtesy of John Randall.

Perhaps the biggest difficulty in keeping these fish is obtaining
a balanced mix of tank mates compatible with the damsel. This
may as well be the impossible journey, however, because unless
the aquarium is of considerable size, the damsel likely will
sternly object to sharing its domain with another fish. The
best chances of success would be to allow the less aggressive
fish to settle within the aquarium long before the addition
of the belligerent damsel. Although this will not guarantee
success, it will help tip the odds in your favor. Fish to
avoid are obviously anything docile such as gobies, small
wrasses, and cardinalfish. Some of the better prospective
tankmates would be anything considerably larger than the damsel
which, at the same time, is unable to swallow the damsel.
Possibilities here are puffers, angelfish, and butterflyfish.
Naturally, any aggressive fish of equal size will work as
well. Such fish would include dottybacks, dwarf angels, and
possibly other damselfish. For the full list, please see below.

Compatibility
chart for Stegastes species:

Fish

Will
Co-Exist

May
Co-Exist

Will
Not Co-Exist

Notes

Angels,
Dwarf

X

Should
co-exist well.

Angels,
Large

X

Should
co-exist well.

Anthias

X

Should
co-exist well.

Assessors

X

Will
likely be harassed and/or killed by the Damsel.

Basses

X

A
large tank should house both with minimal squabbling.

Batfish

X

Damsels
may harass Batfish, attacking excess finnage.

Blennies

X

Should
co-exist well.

Boxfishes

X

Slow
and unable to get out of the way, Boxfishes are likely
to be excessively harassed.

Butterflies

X

Should
co-exist well.

Cardinals

X

Will
likely be harassed and/or killed by the Damsel.

Catfish

X

Should
co-exist well.

Comet

X

Comet
will likely stay hidden more than usual.

Cowfish

X

Will
likely be harassed and/or killed by the Damsel.

Damsels

X

Not
recommended unless paired individuals are obtained.

Dottybacks

X

Should
co-exist well.

Dragonets

X

Ignored
on most occasions.

Drums

X

Will
likely be harassed and/or killed by the Damsel.

Eels

X

Should
co-exist well.

Filefish

X

Likely
to be harassed, especially Chaetoderma pencilligera.

Frogfish

X

May
attempt to consume Damsel.

Goatfish

X

Will
likely be harassed and/or killed by the Damsel.

Gobies

X

Varies
greatly between species, but the majority will be harassed.

Grammas

X

Will
likely find a quiet corner and never move from it.

Groupers

X

Will
co-exist until they are large enough to swallow the Damselfish.

Hamlets

X

Will
be susceptible to Damselfish attacks.

Hawkfish

X

Should
co-exist well.

Jawfish

X

Not
recommended, but once established a jawfish can hide in
its burrow and escape damselfish attacks. May remain mostly
hidden.

Lionfish

X

May
attempt to consume Damsel.

Parrotfish

X

Should
co-exist well.

Pineapple
Fish

X

Should
co-exist well.

Pipefish

X

Will
likely be harassed and/or killed by the Damsel.

Puffers

X

Another
slow mover that may be the object of frequent, repeated
attacks.

Rabbitfish

X

Should
co-exist well.

Sand
Perches

X

Aggressive
enough to holds its own, but it may consume smaller damsels.

Scorpionfish

X

May
attempt to consume Damsel.

Seahorses

X

Will
likely be harassed and/or killed by the Damsel.

Snappers

X

May
attempt to consume Damsel.

Soapfishes

X

Large
individuals may attempt to consume Damselfish.

Soldierfish

X

Lack
of defense may be enough to warrant attention from large
Damselfish.

Spinecheeks

X

Will
hide continually in the presence of an aggressive fish.

Squirrelfish

X

Lack
of defense may be enough to warrant attention from large
Damselfish.

Surgeonfish

X

Should
co-exist well.

Sweetlips

X

May
attempt to consume Damsel.

Tilefish

X

Tilefish
do not mix well with aggressive fish.

Toadfish

X

May
attempt to consume Damsel.

Triggerfish

X

Should
co-exist well except with the most aggressive of Triggers.

Waspfish

X

Should
co-exist well assuming Waspfish is unable to swallow Damsel.

Wrasses

X

Should
co-exist well except for the small docile wrasses.

Note:While many of the fish listed
are good tank mates for Stegastes species, you should
research each fish individually before adding it to your aquarium.
Some of the mentioned fish are better left in the ocean or
for advanced aquarists.

Quite the conundrum is Stegastes insularis. It
is very abundant at depths shallower than 15 feet, seemingly
making it easy to locate. However, it has only been
found at two islands, Christmas Island and Marcus Island
- roughly 6,300km apart. Photo courtesy of John Randall.

Invertebrates are, for the most part, ignored
by damsels. Possible exceptions would be small corals placed
into their territory that they object to. Although they will
not intentionally harm the coral, they will redecorate the
aquarium to suit their desires and in doing so may disturb
the coral enough to cause stress. Mobile invertebrates, such
as snails and crabs, will also be subject to periodic eviction,
although this is obviously of less concern.

Food items offered should consist primarily
of prepared algae diets, but an occasional mix of carnivorous
foods are also appreciated. Algal foods, such as the dried
algae commonly called nori at oriental food stores, are some
of the popular options, but many frozen, freeze-dried, and
pellet options abound. In regard to meaty foods, enriched
brine shrimp and mysid shrimp will adequately fill this void.
This is especially important for juveniles as a larger portion
of their diet consists of copepods due to their lack of an
algae farm. Additionally, harvesting the damsel's farmed algal
bed would not be a good idea no matter how much you despise
filamentous algae. In fact, you may wish to encourage its
growth prior to adding the damsel, but allowing it to take
over the aquarium would be going too far.

Stegastes aureus, appropriately called the Golden
Gregory, is often considered the best looking member
of the genus. It is, after all, the only species which
is not predominantly brown or black at full adult coloration.
Unfortunately, it is not common in the wild, and thus
not common in the hobby. Photo courtesy of John Randall.

The optimum aquarium size for a damsel
can vary greatly depending on your interest in mixing other
fish species with them. A lone individual will do well in
a 40-gallon aquarium provided you do not intend to mix less
docile inhabitants with it. Multiple young juveniles will
do well in the same aquarium, but as they age and grow they
will need to be separated to a minimum of paired individuals.
Otherwise, the weakest individuals will be subjected to constant
harassment and death will likely soon follow. The aquarium
rockwork and aquascaping do not call for anything out of the
ordinary. Traditional aquascaping which provides options for
an open sandbed and also a place for the fish to retreat and
become completely hidden, are key elemental considerations.
These fish will spend more than 90% of their daylight hours
in the water column, but they still need a place to hide and
disappear in the evenings.

Stegastes obreptus prefers to occupy murky water.
It lives so close to shore that a constant wave action
stirs the silt from the bottom. The preserved bodies
of the juvenile (left) and adult form (right)
are pictured here. Photos courtesy of John Randall.

Meet the Species

Possibly
the most common Stegastes damselfish is S. planifrons,
the Threespot Damsel. You'd be hard pressed
not to find a plethora of these damsels on the reefs across
the Caribbean. However, their lack of an attractive adult
coloration doesn't warrant a high degree of demand within
the aquarium trade. The results in an extremely affordable
fish that is rather plentiful, but that also lags in sales.
Those that do sell are the juveniles, which unlike the adults,
have exquisite coloration. Reaching a maximum adult size of
five inches, they can be extremely aggressive. As juveniles,
they mimic Holocanthus tricolor. The common name is
obviously taken from the juvenile color form which sports
a single spot on each side just underneath the dorsal fin,
and a single spot at the base of the tail.

As an endemic of the Coral Sea, Stegastes gascoynei
has little chance of appearing in the American marine
aquarium trade. Photo courtesy of John Randall.

A damselfish with an attractive adult (for Stegastes)
is Stegastes variabilis, the Cocoa Damselfish. Juveniles
are predominantly yellow and royal blue, but eventually this
gives way to the more traditional Stegastes coloring
of dark brown or black with accents of blue and yellow. These
are among the least aggressive members of the genus. During
spawning they are similar to their cousins, but otherwise
they make little effort to defend territories. This is because,
unlike most members of Stegastes, they do not often
setup a true territory, opting instead to patrol open sand
areas. Because they are not farming their own algae patch,
they also have different feeding requirements. In addition
to algae and detritus, tunicates and feather dusters are at
risk of being consumed.

Up to 1,000 individuals of Stegastes nigricans
have been observed on a single rubble zone flat, loosely
occupying the same territory and working in conjuction
with one another to drive away any intruding herbivorous
fish. The juvenile (above) and adult (below)
color forms are pictured here. Photos courtesy of John
Randall.

Another Stegastes not subscribing to the algae farm
concept is S. partitus, the Bicolor Damsel. This species
forms small aggregations of roughly 10-20 individuals and
feeds on plankton in the water column several feet above their
hideouts. Their feeding tendencies are more similar to the
damselfish known as Chromis than with most other Stegastes,
but they remain every bit as fierce to intruders as the typical
Stegastes species. In fact, this species will greet
intruders in squadron formation; each member of the local
hierarchy is quick to join in the defense of their patch reef.

A rather striking example of the Bicolor Damsel, Stegastes
partitus. Photo courtesy of John Randall.

Conclusion

Damselfish
fill the niche of a fish meant for the beginning aquarist
rather well. They withstand less than ideal water parameters
and remain disease resistant, allowing aquarists to learn
the hobby without killing large numbers of fish. At the same
time, an advanced aquarist can settle in with the knowledge
that they will have years of success keeping a fish with an
interesting personality. Regardless of which category you
represent, do not make the mistake of trying to mix numerous
other small, defenseless fish with Stegastes species.

The Blunt-snout Damsel, Stegastes lividus, is
seen here in both the juvenile (top) and adult
(bottom) forms. Note the change in the facial
structure, hence contributing to its common name. Photos
courtesy of John Randall.

If
you have any questions about this article, please visit my author
forum on Reef Central.

References:

Allen, G.R. and A.R. Emery, 1985. A review
of the Pomacentrid fishes of the genus Stegastes from
the Indo-Pacific, with descriptions of two new species. Indo-Pac.
Fish. (3):31 p.